How can we calculate ([Due Date]- [Today])/7 column that updates daily as value of Today changes and lets us calculate weeks left for due date ? Could create ([Due Date]- Today() )/7 and it worked fine but it value of Today() in this is not dyanmic and changes only when we edit an existing entry or create a new one . Any ideas as how to achieve display of weeks left for due date dynamically ?

Unfortunately because of the much larger amount of information
SharePoint has to pass back and forth, it takes a different approach
to updating the data items. It will only update calculated values when
the related item is added or edited.

Consider SharePoint as an overworked secretary; if you ask for a file
to be updated they’ll find it in the filing cabinet, update the
information, and correct anything else that’s awry on the paperwork
while they’re there. If you ask for all the files for people named
“Smith” to be put on your desk, unless you specifically say “And
update the information on every single one while you’re at it”, it’s
not likely they’ll do the extra work for no reason.